Barbed hose fittings have long existed in the prior art. Such fittings come in all shapes and sizes, with many materials and applications. But barbed fittings have many disadvantages. When the hose is compressed on top of the barbs, the sharp and pointed barbs often damage the integrity of the hose, compromising the integrity of the coupling seal, potentially causing leakage. Barbed fittings are difficult to remove once installed in a hose and often cannot be taken out of the hose without causing damage. Additionally, the sharp edge of a barb often causes a scraping on the inside of the hose during application. For hose and fitting combinations with high pressure carrying capability, installation may require tools.
One attempted solution is present in U.S. Pat. No. 6,010,162 to Grau et al. This patent discloses a hose nipple with at least one circular groove with o-ring. This device uses deeper grooves to hold the o-ring, with “protection and support diameters being larger than said O-ring seal diameter.” (Grau, Col. 6, II 48-49). The centerline of the o-ring is below the surface of the hose nipple, resulting in over half of the o-ring being enclosed by the nipple. This results in a less-effective seal because only a small portion of the o-ring is exposed and in contact with the sealing surface of the hose. This device further includes “barbed serrations” which tend to damage the inner layer of the hose. Finally, this device requires the use of clamps carefully placed over the o-rings in order to properly seal. Misplaced clamps, or the use of ferrules, will result in improper compression, and a poor seal.
Another attempted solution is present in U.S. Pat. No. 6,460,897 to Manuli. This patent discloses a connector for flexible pipes (i.e. hoses), particularly for cooling systems. The connector uses a sealing ring that is wider than it is thick (known in the industry as a “D-ring”) to avoid rolling/displacing the sealing ring when a hose is slid over the connector. This, therefore, requires the use of non-standard o-rings to prevent the o-ring from being displaced by the leading edge of the hose during installation. Additionally, the use of a D-ring spreads out the force of the ring against the inside of the hose, decreasing the pressure against the hose, making it more difficult to achieve a high pressure seal.
What is needed is a hose fitting system that seals a hose to a fitting interface end without the use of barbs, providing a strong seal for both lined and unlined hose.